{"id":105178,"date":"2021-05-04T07:00:01","date_gmt":"2021-05-04T14:00:01","guid":{"rendered":"https:\/\/devblogs.microsoft.com\/oldnewthing\/?p=105178"},"modified":"2023-07-20T06:36:26","modified_gmt":"2023-07-20T13:36:26","slug":"20210504-01","status":"publish","type":"post","link":"https:\/\/devblogs.microsoft.com\/oldnewthing\/20210504-01\/?p=105178","title":{"rendered":"A map through the three major coroutine series"},"content":{"rendered":"

Our long national nightmare is not yet over<\/a>: The three main coroutine series are now done, although that doesn’t mean I’m done with coroutines.<\/p>\n

Here’s a map through the main series, at least. There is a direct route and a number of scenic routes.<\/p>\n

Part the First: Awaitable Objects<\/h2>\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
Start the first part<\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n <\/td>\n <\/td>\n<\/tr>\n
C++ coroutines: Getting started with awaitable objects<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n C++ coroutines: Constructible awaitable or function returning awaitable?<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n C++ coroutines: Framework interop<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n C++ coroutines: Awaiting an IAsyncAction without preserving thread context<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n<\/tr>\n
C++ coroutines: Short-circuiting suspension, part 1<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n <\/td>\n <\/td>\n<\/tr>\n
C++ coroutines: Short-circuiting suspension, part 2<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n C++ coroutines: no callable ‘await_resume’ function found for type<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n<\/tr>\n
C++ coroutines: Defining the co_await operator<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n C++ coroutines: The co_await operator and the function search algorithm<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n C++ coroutines: The problem of the synchronous apartment-changing callback<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n C++ coroutines: The problem of the DispatcherQueue task that runs too soon, part 1<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n C++ coroutines: The problem of the DispatcherQueue task that runs too soon, part 2<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n C++ coroutines: The problem of the DispatcherQueue task that runs too soon, part 3<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n C++ coroutines: The problem of the DispatcherQueue task that runs too soon, part 4<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n<\/tr>\n
You made it to the end of the first part<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Part the Second: Awaitable Signals<\/h2>\n

The early portions are optional, but things get interesting toward the end of the second part, where we build a “result holder”.<\/p>\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
Start the second part<\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n <\/td>\n <\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n Creating a co_await<\/code> awaitable signal that can be awaited multiple times, part 1<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n <\/td>\n <\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n Creating a co_await<\/code> awaitable signal that can be awaited multiple times, part 2<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n <\/td>\n <\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n Creating a co_await<\/code> awaitable signal that can be awaited multiple times, part 3<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n <\/td>\n <\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n Creating a co_await<\/code> awaitable signal that can be awaited multiple times, part 4<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n <\/td>\n <\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n Creating a co_await<\/code> awaitable signal that can be awaited multiple times, part 5<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n <\/td>\n <\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n Creating a co_await<\/code> awaitable signal that can be awaited multiple times, part 6<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n Creating other types of synchronization objects that can be used with co_await<\/code>, part 1: The one-shot event<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n Creating other types of synchronization objects that can be used with co_await<\/code>, part 2: The basic library<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n Creating other types of synchronization objects that can be used with co_await<\/code>, part 3: Parallel resumption<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n Creating other types of synchronization objects that can be used with co_await<\/code>, part 4: The manual-reset event<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n Creating other types of synchronization objects that can be used with co_await<\/code>, part 5: The auto-reset event<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n Creating other types of synchronization objects that can be used with co_await<\/code>, part 6: The semaphore<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n Creating other types of synchronization objects that can be used with co_await<\/code>, part 7: The mutex and recursive mutex<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n Creating other types of synchronization objects that can be used with co_await<\/code>, part 8: The shared mutex<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n Creating other types of synchronization objects that can be used with co_await<\/code>, part 9: The shared mutex (continued)<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n Creating other types of synchronization objects that can be used with co_await<\/code>, part 10: Wait for an event to clear<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n<\/tr>\n
Creating a task completion source for a C++ coroutine: Producing a result<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n <\/td>\n <\/td>\n <\/td>\n <\/td>\n<\/tr>\n
Creating a task completion source for a C++ coroutine: Producing a result with references<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n <\/td>\n <\/td>\n <\/td>\n <\/td>\n<\/tr>\n
Creating a task completion source for a C++ coroutine: Producing nothing<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n <\/td>\n <\/td>\n <\/td>\n <\/td>\n<\/tr>\n
Creating a task completion source for a C++ coroutine: Failing to produce a result<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n <\/td>\n <\/td>\n <\/td>\n <\/td>\n<\/tr>\n
You made it to the end of the second part<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Part the Third: Coroutine Promises<\/h2>\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
Start the third part<\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n <\/td>\n <\/td>\n<\/tr>\n
C++ coroutines: The mental model for coroutine promises<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n <\/td>\n <\/td>\n<\/tr>\n
C++ coroutines: Basic implementation of a promise type<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n <\/td>\n <\/td>\n<\/tr>\n
C++ coroutines: The initial and final suspend, and improving our return_value method<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n C++ coroutines: What happens if an exception occurs in my return_value<\/code>?<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n<\/tr>\n
C++ coroutines: Making the promise itself be the shared state, the inspiration<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n <\/td>\n <\/td>\n<\/tr>\n
C++ coroutines: Making the promise itself be the shared state, the outline<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n <\/td>\n <\/td>\n<\/tr>\n
C++ coroutines: Building a result holder for movable types<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n <\/td>\n <\/td>\n<\/tr>\n
C++ coroutines: Accepting types via return_void<\/code> and return_value<\/code><\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n <\/td>\n <\/td>\n<\/tr>\n
C++ coroutines: Awaiting the simple_task<\/code><\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n <\/td>\n <\/td>\n<\/tr>\n
C++ coroutines: Managing the reference count of the coroutine state<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n C++ coroutines: The lifetime of objects involved in the coroutine function<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n C++ coroutines: Tradeoffs of making the promise be the shared state<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n<\/tr>\n
C++ coroutines: Making it impossible to co_await<\/code> a task twice<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n <\/td>\n <\/td>\n<\/tr>\n
C++ coroutines: Getting rid of our mutex<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n <\/td>\n <\/td>\n<\/tr>\n
C++ coroutines: Getting rid of our reference count<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n C++ coroutines: Allowing the awaiter to be destroyed while suspended<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n C++ coroutines: Getting rid of our atomic variant discriminator<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n C++ coroutines: Cold-start coroutines<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n C++ coroutines: Improving cold-start coroutines which complete synchronously<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n C++ coroutines: Associating multiple tasks with the same promise<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n<\/tr>\n
C++ coroutines: What does it mean when I declare my coroutine as noexcept?<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n <\/td>\n <\/td>\n<\/tr>\n
C++ coroutines: How do I create a coroutine that terminates on an unhandled exception?<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n <\/td>\n <\/td>\n<\/tr>\n
C++ coroutines: Snooping in on the coroutine body<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n <\/td>\n <\/td>\n<\/tr>\n
C++ coroutines: Adding custom resume context support to our awaiter<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n C++ coroutines: Waiting synchronously for our coroutine to complete<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n C++ coroutines: Converting among tasks that use the same promise<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n\u00a0<\/td>\n <\/td>\n<\/tr>\n
C++ coroutines: Promise constructors<\/a><\/td>\n<\/tr>\n
\u00a0<\/td>\n <\/td>\n <\/td>\n <\/td>\n<\/tr>\n
You are here<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

I’m not done with coroutines, but this is a road map through the three main areas.<\/p>\n","protected":false},"excerpt":{"rendered":"

For your casual reading convenience.<\/p>\n","protected":false},"author":1069,"featured_media":111744,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[1],"tags":[25],"class_list":["post-105178","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-oldnewthing","tag-code"],"acf":[],"blog_post_summary":"

For your casual reading convenience.<\/p>\n","_links":{"self":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/posts\/105178","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/users\/1069"}],"replies":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/comments?post=105178"}],"version-history":[{"count":0,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/posts\/105178\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/media\/111744"}],"wp:attachment":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/media?parent=105178"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/categories?post=105178"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/tags?post=105178"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}